Recently, with regard to processing of a silver halide photographic light sensitive material (hereinafter, simply referred to as photographic material), shortening of processing time has been demanded. In the field of X-ray films for medical use, the amount of X-ray photographing is rapidly increasing due to increased use of X-rays for diagnosis and inspection in general medical examinations, as well as the increased tendency for periodical medical check-ups and clinical surveys. As a result, the desire for still faster processing is raised.
Shortening of processing time including developing, fixing, washing, drying, etc. is the key for faster processing of photographic materials. Shortening of the developing time alone, however, leads to a marked decrease of image density and sensitivity and deterioration of contrast. Shortening of only the fixing time leads to insufficient fixing, causing deterioration of image quality. Furthermore, shortening the time of each processing step results in incomplete dye leaching out of the processed material, causing stains due to residual dye.
To overcome these problems, it is basically required to enhance developability and fixability of the photographic material, reduce the content of the dye and promote release or decoloration of the dye.
To prevent dye stains, as is well known, it is effective to reduce the binder content. However, reduction of the binder results in marked deterioration in pressure resistance or causes problems such that when being subjected to rapid processing, abrasion marks are produced by the rollers of an automatic processor, or when being bent, pressure fogging or pressure desensitization occurs.
For environmental protection, reduction of processing effluent is required, and therefore, reduction of the amount of processing solutions and replenishing solutions or exhaustion of the processing solutions is required. In this case, however, various problems also occur similarly to the case of the above-described rapid-processing.
As techniques for solving these problems, for example, examined Japanese Patents 43-4931 and 44-16589, EP-0,506,584 (hereinafter, the term, "EP" refers to European Patent) and JP-A 5-88293 and 5-93975 (hereinafter, the term, "JP-A" refers to unexamined and published Japanese Patent Application) disclose a technique of using, as a sensitizing dye, benzimidazolo-carbocyanines which are superior in decolorizability. JP-A 5-61148 discloses a technique in which a combination of an oxacarbocyanine and benzimidazolocarbocyanine is used in a specific proportion, in a silver halide emulsion containing 1 mol % or less iodide and the silver halide emulsion is further chemically sensitized with a selenium compound and/or tellurium compound.
The dye stain reduction and rapid-processability can be improved by these techniques, but it is not insufficient to satisfy other desired levels. Specifically, since the absorption maximum of a photographic material is in a longer wavelength region and sensitivity to red light is too high, fogging due to safe-light is markedly increased. Furthermore, another defect is that when aged under high temperature and high humidity, the decrease in sensitivity is marked.
There have been made a variety of basic studies with regard to the relationship between the surface of silver halide grains and adsorption of sensitizing dyes. Phot. Sci. Eng. 18 215-225 (1974) describes that when a sensitizing dye is adsorbed to silver halide grains having (100) faces, desensitization in intrinsic sensitivity of the silver halide grains is small. It is also described that when chemical sensitization is carried out in the presence of a sensitizing dye, the chemical sensitization is controllable and desensitization in intrinsic sensitivity can be reduced. However, these techniques suggest nothing with respect to the technique of pressure resistance.
Silver halide photographic light sensitive materials generally have characteristics relating to intensity reciprocity law failure and the characteristics are variable, depending on properties of processing solutions. Specifically, low intensity reciprocity law failure is easily affected by developing agents, which results in a problem that when exposed over a long period of time, the decrease in sensitivity is markedly large, and therefore improvement in this art has been greatly desired.
Also, in the field of photographic materials for medical use, simplification and security of overall processing are being promoted to enhance working efficiency. With regard to processing chemicals, one conventional system is that a commercially available condensed processing solution is diluted to a given amount and the resulting solution is supplied as a replenisher to the processing tank of an automatic processor. As a result, the processing solution is massive in weight and volume, with the inherent disadvantages that enhancement in efficiency and safety of processing is difficult to achieve. Instead thereof, recently, there was proposed a system of solid processing chemicals, in which the processing chemicals are supplied in the form of a solid processing composition and diluent water. With this system, there have been achieved improvements in working efficiency as well as lowering of transportation cost and reduction of storage space. In addition, the amount of packaging material such as plastic resin, was advantageously reduced.
However, this system still has problems such that as processing chemicals are solid composition, its solubility (dissolution speed) is concerned and when subjected to ultra-high speed processing, stable running performance can not be achieved.
In developer used for black-and-white photographic light sensitive materials, dihydroxybenzenes such as hydroquinones have been conventionally employed as a developing agent. Recently, it was proposed to substitute ascorbic acids for the developing agent in terms of improvements in safety of working and environmental protection; for example, U.S. Pat. No. 5,236,816 discloses developing solutions employing ascorbic acid.
However, the developing solutions employing ascorbic acids are lower in activity and worse in aging deterioration than those which use hydroquinones, resulting in disadvantages that stable photographic performance can not be realized. There has been desired a silver halide photographic material developable with a developing agent such as ascorbic acid, and eliminating use of hydroquinones.